This project continues to focus upon the different clinical forms of leishmanial infections in humans, the cell-mediated immune responses to leishmanial antigens, and characteristics of the causative parasites. Six parasitologically proven cases of cutaneous leishmaniasis were diagnosed and treated at the NIH Clinical Center during the past year. Many additional patients referred to the NIH by local military services (Walter Reed Army Medical Center and National Medical Center) were evaluated by cell-mediated immunologic studies and leishmanin skin tests for evidence of past or present leishmanial infection. Many of these cases were leukophoresed to obtain lymphocytes for research purposes. Leishmania tropica, a species that traditionally has been associated with cutaneous leishmaniasis, has been isolated from bone marrow of five Desert Storm operation veterans, and from the lymph node of at least two additional cases. The clinical picture in many of these cases is atypical, and immunologic tests suggest that many additional systemic leishmanial infections have occurred. Semi-quantitative PCR techniques were employed for detection of mRNA of various cytokines in bone marrow specimens from patients with visceral leishmaniasis (Kala-azar) in the Sudan. Relatively high levels of mRNA for IL-10 appear to be present in active cases, with a marked decrease in levels after treatment. These findings may help explain the antigen- specific anergy that occurs with this disease.